This invention relates to apparatus for the dry spinning of filaments. More particularly, it relates to apparatus for spinning acrylic filaments with provision for distributing heated gas to the outside of the filament bundle and to the center of the filament bundle from the outside heated gas source.
In the manufacture of acrylic fibers by the dry spinning process, a solution of the acrylonitrile polymer in a volatile, inert organic solvent is pumped through a spinning pack and extruded through the spinneret orifices as a multiplicity of streams. A heated gas, comprising an inert gas hotter than the solution, is impinged against the extruded streams to evaporate part of the solvent, reducing the solvent content from about 60-75% to about 20-30% and forming filaments of the polymer. Conventionally, the orifices are arranged in concentric rings around a blank central portion of the bottom surface of the spinneret of the spinning pack.
For increased spinning productivity, it is desired to spin as many filaments simultaneously as possible. One limitation to productivity is distribution of the heated gas uniformly through the filaments.